Method of separating gases or the like



I April 1946. N. c. TURNER 2,398,817

METHOD OF SEPARATING GASES OR THE LIKE v I Filed NOV. 13, 1940 2Sheets-Sheet l April 23,1946. N. c. TURNER METHOD OF SEPARATING GASES ORTHE LIKE Filed Nov. 13, 1940 2 Sheets-Sheet 2 INVENTOR.

W C 7M BY W M I AM PM... Apr. 23, 1946 UNITED STATE METHOD OF SEPARATINGGASES OR THE LIKE Nelson C. Turner, Tulsa, Okla.

Application November 13, 1940, Serial No. 365,415

' 7 Claims.

This invention relates to a method of separating case's. vapors orliquids, particularly light hydrocarbon gases or vapors such asordinarily occur in natural gas, the method hereinafter described bein:particularly intended for laboratory analysis, although it may also beutilized for industrial gas fractionation.

The method of separating light hydrocarbon gases most generally employedconsists in the condensation of the hydrocarbons at low temperatures bycooling, with liquid air, and then fracpoint between two successivehydrocarbons is often ill-defined and leaves much to human jud ment inthe determination of the volume of the component which has beendistilled.

In accordance with the present invention, the use of liquid air or otherlow temperature cooling medium is dispensed with. The method inventionemployee a substance capable of adsorbing the gases which are to beseparated and means for driving the pure gas fractions from saidadsorbing material in the sequence in which they are released byfractional distillation.

The present invention provides sharper separation between the individualcomponents of the gas than was possible heretofore. It also provides amuch more rapid analysis which in some instances may be completed inabout one-fifth oi the time required by the low temperaturefractionating method.

The invention will become more apparent from a consideration of theaccompanying drawings in which like reference characters designate likeparts and in which:

Fig. 1 is a diagrammatic view of apparatus for separating gasesembodying the principles of this invention;

Fig, 2 a side elevational view partially in section oi a fractionationcolumn;

Fig. 3 a view diagrammatically illustrating a portion of thefractionating column and adjust-' able heating means therefor;

Fig. 4 a diagrammatic illustration of an adjustable manometer coupled toa plurality of electronic relay control circuits; and

Fig. 5 a diagrammatic view of a fractionating umn to unusual problems.

column and mechanically adjustable heater and mercury container.

With reference to Figs. 1 to 3 inclusive of the drawings, the numeral Idesignates a gas fractionating column having progressively reducingcross-sectional areas forming chambers of such proportion that theinternal cross-sectional area at the outlet end 2 is only a smallpercentage of the internal cross-sectional area of chamber 3 at theinlet or entrance end of the column. The column may be provided withthis 4 for rapid heating and cooling.

The fractionating column I is filled with an adsorbing material such asactivated cocoa-nut shell charcoal I, Fig. 3, and a heating means suchas an electrical heater 5 is provided to drive the gases out of theadsorbent material. Heater 5 is movable vertically of the column, asshown in Fig. 5, it being shown in the extreme bottom position in Figs.1 and 5, and moved slightly upward in the position of Fig. 3, the heatbeing applied locally beginning at the large end of the column;

Mercury from a movable reservoir 6 is introduced part-way into theheated zone ofthe column to bring it to the boiling point, and itsvapors are employed to' clean the adsorbent charcoal of the adsorbedgases. As the adsorbent in the lower zones is freed of gases, the heater5 and mercury reservoir 6 are raised to a fresh portion of the packingto successively drive off the gases in succeeding zones. The heater ismovable with the mercury container by means of a yoke 6 and a motordrive.

In Fig. 5,the mercury container 6 is of annular form and movable on acolumn 6. It is supported by a cable 6 passing around pulley 6 downthrough the column and around pulleyt a drive drum 6 and a spring biasedtake-up drum 6 Drum 6' is driven by a motor 6 which is controlled by anelectronic relay 59, Fig. 4.

The mercury container 6 is connected by a fiex ible conduit 6 to thebottom of the fractionatina column I. Valved connections 6 and 6* ofFig. 3 are provided, one for admission of samples and the other for thepurpose of flushing-out the sampling lines.

As shown in the drawings, the fractionatina column is generally. mountedvertically with its larger end at the bottom. It may, however, be placedin a reclining position or oriented in any other way for special uses inadapting the col- A by-pass tube I, Fig. 1, may be connected into thecolumn at some point along its length to indicate during sampling theprogress of the heavier constituents oi the mixture being adsorbed. Theby-pass tube is provided with a valve 8 so that the gases may be forcedto leave the column through the small outlet end 2, controlled by valve9, from which the gases pass to enter the condenser l3 from separator Iand by a capillary tube. I4 pass to a junction I5 which is connected tothe low pressure side of an adjustable manometer l5, Figs. 1 and 4, andfrom which the gas flows to a volumeter II through a thermalconductivity cell l8 and a temperature equalizing coil 20.

The high pressure side of manometer I5 is connected to separatingchamber ill by tubing I 9, but there isno gas flow through I9 because ofthe liquid seal in the manometer. The gases pass through the thermalconductivity celll8, then through a temperature equalizing coil 20,which is connected to the top of the volumeter ll. The thermalconductivity cell I8, coil 20 and the volumeter ll may be immersed in aconstant temperature bath contained in a tank 2|; agas outlet 22 extendsfrom the volumeter, as shown in Fig. 1; or gases may be withdrawn fromoutlet :2, Fig. 1. v

Fig. 4 shows arrangements of contacts 61 and 68 of the electronic relay59 with the manometer.

The manometer I6 for the automatic control of the gas flow during thedistillation consists of a U-tube having a bulb I6 and a tube I5", the

- mixture have penetrated the latter having graduations I5. Numerals I6and I Ii designate the water levels in the manometer which are anindication of the rate of flow of the gases in line ll, Fig. l Thebellows adjustment provides for slight variations in rate at which gasflow is maintained, major variations of rate being controlled bychanging size of capillary I4, Fig. 1.

The motor 5 which raises, the heater 5 and mercury chamber 6, and theenergization of heater 5 is controlled through relays 59 by rate of gasflow through capillary I4 by means of the manometer I 5. in bulb I5 areconnected to contacts 61 and 68 of a pair of relays 59. Electrode II islonger than I2 and controls the motor circuit which moves the heater 5vertically on the fractionating column I.

The water in the U-tube is electrically connected in the relay circuitby conductor 13.

traversing the ,fractionating column I exceeds a predetermined amount,the level of the water l6 makes contact with terminal Ii and energizesrelay 59 to cut out the motor 6 thereby stopping further movement of theheater 5 on the column. If the gas flow nevertheless continues toincrease, the level I5 of the water column will contact terminal 12which, through the electronic relay 59, deenergizes the heater 5. Whennormal gas flow has been re-established the level Iii drops below theends of terminals H and I2, and the drive and heating units are againenergized to continue normal operation of the fractionating column. a

The operation of the above-described gas trac- Terminals II and I2disposed When the flowof gases generated by heater 5 pressure.

are adsorbed by the charcoal I and when the column I is filled, asindicated by a change in thermal conductivity of eiiiuent gas, the valveof the connection 6* is shut-0H.

The by-pass valve 8 may be opened during sampling to indicate theprogress of the heavier constituents oi the mixture being adsorbed. Thesample is drawn oil through the by-pass I until a slight change in thecomposition of the effluent gas indicates that the heavier components ofthe packing to the point at which the by-pass begins. then discontinuedand distillation of the sample is commenced, with the by-pass valve 8closed and valve 9 open.

Mercury reservoir 6 is then raised enough to introduce mercury into-theentrance end 3 of the column, and. heater 5 is energized and the gasfractions are driven from the adsorbing charcoal material of the heatedportion of the column into the upper sections of the column.

As the body of the adsorbed components is driven up through theadsorbent the tendency of the heavier components to remain behind issufll ciently pronounced to causethe individual components to separateinto layers, each layer consisting of substantially pure component. Asthe various components are driven through the adsorbent bed by theaction of the heater, the stratum between any two adjacent components,which contains substantial quantities of both components, finallyreaches a limited minimum thickness dependent upon the relativeadsorption characteristics of the two components. In order that thevolume of mixed gases in this stratum may be reduced to a negligiblevalue in comparison to the volume'of pure components above and below it,the cross-section of the adsorbent bed at the outlet end of the columnis substantially less than the cross-section at the charging end. Sincethe thickness of the stratum of mixed components is independent of thediameter of the cross-sectional area of the adsorbent bed, the volume oradsorbed components in this stratum will decrease in direct proportionto the crossare delivered from the top of the column.

The separated gases pass out of the column through the condenser I3 andseparator, and flow through the capillary tube I 4, past connectionblock I5 of the manometer I6, and to the thermal conductivity sell I 8from which they pass to the volumeter II.

The volumeter may be adapted for use in measuring very small amounts ofgas or for metering corrosive gases or for. other specializedapplications. It may be provided with a saturating chamber where the gasis bubbled through a quantity of the sealing liquid to minimize errorsintroduced by.varying humidity of the samples under observation. It mayalso be provided with a safety chamber to prevent drawing the liquidback into the inlet line in case of reversal of As previously explained,the manometer I 5 controls the rate 01' gas flow by controlling movementof the heater and the heat supplied to the fractionating column throughthe relays 58 in the The sampling is manner shown in Fig. 4. The normalrate of flow, as established by the capillary [4 operating manometer I6, may be varied by adjustment of.

the bellows I 6 by screw I6 if desired.

The volumeter measures the total volume of gas passing out of the columnduring the time between consecutive changes in composition. From arecord of the volumes of the various fractions as measured and thetemperature and barometric pressures, the volume percentage of thevarious components may be calculated. The outlet connection 2'4."provides for the collection of isolated fractions in their purifiedstate.

After completion of distillation of a sample, the column is preparedforthe next run by lowering the mercury reservoir and heater to. theirinitial positions at the bottom of the column. While the mercury isbeing lowered, some gas such as air or hydrogen is allowed to enter thecolumn through the connection I l. The use of hydrogen rather than airis helpful in the analysis of natural gases and other similar samplessince it is readily displaced and permits the sampling to proceed at agreater rate. In cases where these gases might interfere with theanalysis of the sample, the column may be sealedduring the lowering ofthe mercury reservoir and the sample admitted to the evacuated column.An especially constructed column in which the mercury reservoir could belowered approximately one meter below the sample inlet connection wouldbe necessary for useof this vacuum technique.

By means of. the reduction in' area or the column the bulk of theadsorption of gases is made to occur near the entrance end and a longchamber is provided substantially free of the heavier components of gasmixture for refractionation and further purification of the fractions aSthey approach the outlet end. The mercury entering the bottom of thecolumn not only drives the adsorbed gases out of the adsorbent but alsoseals theadsorbent material during distillation so that readsorption ofgases from another portion of the column cannot take place during thedistillation.

Means other than the electric heater may be employed for driving thegases out of the adsorbent. However, the electric heater and the movablemercury reservoir are found to be very practical because when the heatis applied locally, beginning at the large end of the column, themercury from the movable reservoir is introduced part-way into theheated zone where it is brought to the boiling point and the vaporsclean the adsorbent of the adsorbed gases. As the adsorbent in this zoneis freed of gas, the heater and mercury level are raised to a freshportion of the packing.

The unique construction of the column consisting of consecutive chambersof reducing areas either continuously or in steps, as shown in thedrawings, results in the bulk of adsorption of gases occurring near theentrance or enlarged end of the long chamber which is maintainedsubstantially free of the heavier components of the gas mixture forrefractionation and further purification of the fractions as theyapproach the outlet end.

It will be evident to those skilled in the art that the method ofadsorption and expulsion of gases by a fractionating column, as hereindisclosed. may be practlced with various forms of auxiliary equipmentfor measuring the volume or physical properties of the gases.

I claim: 1. The method of separating gases or vapors which comprisescharging the gases or vapors into one end of an elongated container,applying heat progressively from one end to the other of the containerto expel the gases from the adsorbent material, and replacing theexpelled gases with another vapor to prevent readsorption of theexpelled gases.-

2. The method of separating gases or vapors which comprises charging thegases or vapors into one end of an elongated container, applying heatprogressively from one end to the other of the container to expel thegases from the adsorbent material, and filling the free volume betweenthe granules of the adsorption material with mercury after the heat hasbeen applied.

3. The method of separating gases which comprises passing the gases orvapors through a unitary mass of adsorbent material contained in anenclosed space of gradually reducing cross-sectional area and heatingsaid adsorbent material progressively from the large to the reduced areaof the mass to separate the adsorbed components into fractions of thegases in the sequence in which they are released by the distillation.

4. The method of separating gases which comprises passing. the gases orvapors through a unitary mass of adsorbent material contained in anenclosed space of gradually reducing crosssectional area, heating saidadsorbent material progressively from the large to the reduced area ofthe mass to separate the adsorbed components into fractions of the gasesin the sequence in which they are released by the distillation, and

progressively sealing the heated end of the mass to prevent readsorptionof the released gases.

5. The method of separating gases which comprises passing the gases orvapors through a unitary mass of adsorbent material contained in anenclosed space of gradually reducing cross-sectional area to separatethe components into stratum or fractions of the gases, and applying heatprogressively to the different stratum of the gases to release them inthe sequence of their occurrence. I

6. The method of separating gases which comprises'passing the gases orvapors through a mass of adsorbent material contained in an enclosedspace of gradually reducing cross-sectional area to separate thecomponents into stratum or fractions of the gases, applying heatprogressively to the different stratum of the gases to release them inthe sequence of their occurrence, and regulating the rate of heatapplication to the different stratum torelease the fractions of thegases at a substantially constant rate of flow.

7. The method of separating gases which comprises filling a mass ofadsorbent material contained in an enclosed space ,with hydrogen or

